Tractor semitrailer combination



TRACTOR SEMITRAILER COMBINATI ON Filed May 5, 1938 8 .Sheets-Sheefl l W. H. WILSON ET AL TRACTOR SEMITRAILER COMBINTION Noti'. 28, 1939.

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TRACTOR SEMITRAILER COMBINATION Filed May 5, 1938 8 Sheets-Sheet 5 .III

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TRACTOR SEMITRAILER COMBINATION Filed May 5, 1938 8 SheelS-Shef-Vf,l 6

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NOV. 28, 1939. W, W|| $0N ET AL 2,181,389

TRACTOR SEMITRAILER COMBINATION Filed May 5, 1958 8 Sheets-Sheet 7 ATTORNEYS Nov. 28, 1939. w H, W.. SON ETAL 2,181,389

TRACTOR SEMITRAILER COMBINATION Filed May 5, 1958 8 Sheets-Sheet 8 r ATTOR eim Patented Nov. 2s, 1939 UNITED STATES TRACTOR sEMrrRAILER COMBINATION o William H.

Wilson andCharlesHLLand,

Detroit, Mich.

Applicationf-May 5, 1938,'Serial'-No; 2065135 20 Claims.

This invention relates to a tractor semitrailer combination, and it has to do particularlyzwith improvements by means of which serviceoperations on the semitrailer are obtained. Such service operations may include operation of the trailer brakes. Certain phases of the invention are applicable to the soy-called fully automatic semi-trailer wherein all operationsmay be efected from the drivers'cab of the tractor, and certain phases of the invention may be arranged so that some of the operations may be controlled from the trailerfor the so-oalled semi-automatic semitrailer.

In accordance with the invention the semitrailer is equipped with two types of brake operating means. One of such operating means takes care of brake operation while'the vehicle is in transit or otherwise in use and connected tothe tractor, and'this operating means is preferably of the hydraulic type. nThe other :brake operating means is arranged to take care of the brakes and'hold'thern set when the trailer is parked or lodged separate from thetractor, and this brake operating means may be controlled froml the tractor in the fullyvautomatic type prior to tractor semitrailer disconnection. This brake operating means is preferablyof a mechanical type'forv holding the brakes set over a long yperiod of time, thus releasing the hydraulic system `ofsbrake holding stresser pressure. Preferably, themechanical brake applying andholding meansmay `be controlledfrom the ltrailer so that'the brakes maybe relieved at any time even though @the "trailer is parked.

The controlling mechanism which'may be controlledfrom the cab of the tractor kembodies `essentially two groups of controlling means operable optionally from'the'cabof the tractor. vThe operator may adjust the controlling mechanism in what may be termedr a' normal conditionl so `that while in transit the semitrailer'brakes are operated hydraulically. When an iuncoupling action is about to be accomplished,` the operator may-adjust the mechanismY to. bring the mechanical'brake applying means into'play. lAt this time mechanism is eiective .for operation fromthe cab ofthe'tractor to `release-a device `which'ma-intains the draft coupling. The arrangement may be such that' mechanism `which. is. brought into play at the time an luncoupling action fis-desired operates both to apply the brakesand to release the draft coupling device. In. a'coupling operation, an arrangement is provided in the mechanical brakeoperating means for releasing the brake applying pressure, preferably at or Ynear `cross'section illustrating control devices on the semi-trailer.

the completionaoi the ;cOupling-action. `*Certain Y `noveljeatures of structure for obtaining these Ldifferent actionsare embodied 4inthe structure for carrying outI the invention. `The above `objects `and other objects These drawings illustrate oneiorm of mechanism for icarrying .out the invention.`

Fig 1` is a plan view ofasemitrailer trame emr1.0

portion ofthe semiftrailer and showing part of f1.1.

the tractor. y

Fig. 3 is an enlarged planview illustrating some ofthe mechanism embodied inthe forward end of thesemitrailen Fig.4 is -anenlarged detail vview illustrating r.'20

means Afor 'holding the -Ymechanical Abrakes f applied. l o

Fig.f5,is a side viewofthe mechanismillustrated inFig. 4.

"Fig 6 is an -enlarged view largely-inv cross 25 section illustrating the king pin arrangement and-some of the mechanismfongthe sem'itrailer and tractor.

"Fig. 7 ,is an enlarged detailfview largely in sernitrailer. I

Fig. -8 isa :detail View illustrating some Aof the structure shown in Fig. 7.

Fig 9 is a cross-sectional viewtakensubstantiallyy onfline 9-9 of Fig. '7.

Fig. l0 is a cross sectional view taken substantially on line lll- I0 ofFigf'l.

Fig. 1l is a View showing some ofthe parts illustrated in Fig. 7 in` a yshifted position.

Fig.` l2 is across sectional view illustrating lthe control; mechanism cnr-the upper ,and lowerth wheels -on lthe semitrailer and tractorv respectively. f f y l Fig. 13 is a view illustrating control mechanism f mounted on' the tractor for controlling optionally '45 the actuation of certain operating means on the Fig. 14 is a Iview illustrating the.movements through the king pin.

Fig. l5 isl asectional view taken substantially v(.50

on line I5-l 5 of Fig.A 14.

Fig. 16 is a detailviewwith parts in cross section illustratingthedraft coupling. j

Fig. 1'7 .-isA a view illustrating-the draft couplingandserv-ice bar memberatabout theftime of the 55 will beiully appreciated, kas the vfollowing detailed description is followed in connection with ,the-.accompanying drawings.

completion of the uncoupling movement or the beginning of the coupling movement.

Fig. 18 is a view taken substantially on line Ill-I8 of Fig. 17 illustrating a detent function for the draft latch and showing the coupled relationship of the parts.

In Fig. 1 the chassis of a semi-trailer is illustrated as comprising a frame I with wheels at the rear as illustrated at 2 and it is provided with brakes generally illustrated at 3. 'I'he brake structure per se is not shown. The brakes are arranged to be actuated hydraulically, for which purpose a master hydraulic cylinder is shown at 4' with conduits 5 connecting the brakes. The brakes are also arranged to be operated mechanically, for which purpose there is also illustrated rock-shaft 6 and a brake rod 1. It is within the invention to use the same brake structure 3 to be operated by both the hydraulic system and mechanical system, or separate brake structures may be disposed in the brake housings 3.

Supporting legs are pivotally connected to the frame for supporting the forward end when detached from the tractor, and one of the legs is arrangedto turn its pivot member Sa, upon which is mounted a projecting finger 9 (Fig. 5). A service bar EE! is mounted for reciprocation in the trailer frame, and itis connected to the legs as shown at II. The forward end of the service bar has an abutment or hook I2 arranged to slide in guideways i3. This structure and a draft coupling may be substantially in accordance with that shown in the William H. Wilson application Serial No. 178,853, filed December 9, 1937. 'I'he tractor has a king pin I 4, and pivotally mounted in the trailer frame is a draft ho-ok l5 having a heel I5, Figs. 16 and 17. The forward end of the slot I3 is off-set, or in other words, has an angularly extending portion Il', as disclosed in said Wilson application. The hook I2 pulls the service bar and therefore swings the supporting legs to supporting position as the tractor pulls away, and when the king pin passes through the off-set portion |'I of the guideway, there is a lateral shift between the tractor and semitrailer fifth. wheel members. Suitable means (not shown) may be provided to hold the legs in supporting position. When a coupling is made the tractor backs into the semitrailer and the lateral arrangement causes the king pin to again move back of the hook I2 and the service bar is pushed rearwardly and the supporting legs elevated.

A lock member 20 locks the draft hook around the king pin as shown in Fig. 16. For release purposes the locking member is retracted (Fig. 17) and held retracted by a spring pressed detent 2| (Fig. 18). As the tractor pulls `away the king pin swings the draft hookfrom the Fig. 16 position to the Fig. 17 position. The draft hook is higher than the locking member 25 (Fig. 18) and it engages an inclined surface 22 on the detent and elevates it out of blocking position relative to the locking member 20, and the end of the draft hook then blocks the locking member 20 as shown in Fig. 17. As the coupling is completed the portion 22 of the head which has the hook |2 engages the heel I6 and rocks the draft latch to king pin engaging position (Fig. 16), and inasmuch as the detent 2| has been riding upon the surface of the latch, the locking member 20 moves into a position to hold the draft vlatch around the king pin (Fig. 16)

The above described construction relative to the latch is one form of latch structure which can be used with the present invention and has been described in order to disclose a fully operable mechanism. This latch structure, of course, is subject to variation.

Certain structure is mounted on the tractor, 5 particularly in the so-called fully automatic tractor semitrailer combination, and the tractor may have a rocking fifth wheel member 25 upon which a fifth Wheel member 25 on the under side of the trailer frame rests when in coupled relationship (Fig. 2). As aforementioned, the tractor carries the king pin I4 and this king pin is provided with two controlling pins 2l and 28 which are axially shiftable in the king pin. On the under side of the fifth wheel, there is mounted a rocker shaft 29 (Fig. 13) upon which is splined or keyed a clutch member 3l). Pivotally mounted upon the shaft is an arm or yoke member 3| which has a pin and slotI engagement 32 with the pin 27. Also pivotally mounted on the shaft 29 is 20 an arm or yoke 33 which has a pin and slot connection 34 with the control pin 28. A bell crank 35 is connected to the clutch member 30 and is' normally arranged to be in clutching engagement with one of the arms 3| or 33. As `25 shown a coil spring 36 normally holds the clutch member in engagement with arm 33. A control rod or cable 3l' runs to the cab of the tractor so that the operator, by pulling on the member 3l, may extend the spring 36 and shift the clutch @.30 member 30 to the right (Fig. 13,) to cause it to engage with the member 3|. The clutch member hasa depending arm 4I) connected to a rod 4| which in turn connects to a'piston rod or diaphragm rod 42 in a cylinder o-r chamber 43 35 of a so-called booster. A suitable brake pedal in the tractor isI arranged to apply the brakes and this causes movement of a piston or diaphragm in the booster 43 to pull on the rod 4| and rock the clutch member 30. w

A rock-shaft 45 is pivotally mounted in the trailer and it has an arm 46 overlying the shifting pin 28 (Figs. 6 and 7). There is an arm on this rock-shaft connected by a rod 4'! to operate the piston in the master cylinder 4 on the 2.145 trailer for applying the brakes hydraulically.

It will be observed that due to the spring 36 the clutch member 30 is normally positioned for actuation of the arm 33, pin 28 and shaft 45 to control the brakes of the semtrailer hydrauli-l50 cally. This is the so-called transit operation and at all times during operation of the combined vehicle the brakes may be applied hydraulically through these connections. Fig. 14 illustrates full and dotted lines showing the man` 5:55 ner of the rocking of the arm 46 and shaft 45.

As shown in Figs. 3 and 7, another shaft 5B is mounted in axial alignment with the shaft 45, and this shaft is connected to a brake rod 5| acted uponby a spring 52. The shaft 5I) is jour- .60 naled in a sleeve 53, and clamped to the sleeve is a member with an arm 54 connected by a member 55 to a pivotally mounted arm or bell crank 56. The arm 56 has a bifurcat'ed end which connects to a projecting stud 5'! on the locking memf65 ber 2D. The sleeve 53 has an arm 58 which lies over the pin 21 (Figs. 3, 6 and 9). Therefore upward movement of the pin 21 will rock the sleeve and swing the arm 55 to retract the lock- 'ing member 2D from the Fig. 16 position to the 70 Fig. 17 position.

In this action there is an arrangement which forms a clutching engagement between the shafts 45 and 50. As illustrated in Fig. 7 the shaft 50 is slotted near its end and a pin 6I) extends :175

through'fthe Slot and the :pin is connected to a memberil with "afproj'ecting iinrg'eraSZ. The ,pin l6l! keys themember 6l to the shaft-55. lAnother member 83 'which isjrockabl'e 'n'a bearing 63 on shaft 50 (Fig. '7) hasa sliding pin engagement 64`with the arm 58.A Y'Ihemen'1ber1i3 has a projecting pin `65 operatingin a CamelotI 650i `a xed bracket member 61 whichjis attached to a transverse frame member 18. Vhen the arm 58 is swung upwardly by movement of the pin `21 ltoretract the locking member 2ll,`as above described, themember V63, is caused'to rock with ',thei'sleeve 53' `and arm "53jby reasonof the sliding vmember 12 pivotally mountedas at 13, and the brake rod 1 isalso connected to the ratchet pivotally as at 14. A pawl 15 acted upon by spring 16 engages the ratchet to hold it in position and this pawl is mounted upona shaft 18 journalecl in the frame and which is provided with a handle 19. There is a pawl releasemember 89 pivot- 'ally mounted upon the shaft 'l'and acted upon by a torsionl springt I.

The normal position of the parts is illustrated Vin Figs. 4 Yand 5. When the rod`5i is pulled the 4ratchet is swung counter-clockwise tojapply the brakes, and the brakes a're'held applied by the pawl and ratchet. The brakes may bel relieved ving the pawl by the means of the handle 19.

vWhen the supporting legs 8 are folded or held at any time while the trailer is'parked by swingupwardly in transit position, the projection 9 may be in a position substantially as illustrated in the full Alines in Fig. 5. The `mer'nber 8l! has a nger82 overlying the heel of the pawl. When the legs move to supporting position, -which Inovespring, but this does not aiect the pawl.

`be reiterated 'inv more detail. 1 clutch member 30 on the tractor is in the position ji'shown in Fig.'l3 where it clutches with the "`member`33. Any time the operator wishes to ap- "ply 'the brakes he may depress the brake pedal ment is a clockwise swinging movement on the fulcrum 8a as Fig. 5 is viewed, the projection 9 moves past the swinging member 88, thus moving the member 88 against the action ofthe torsion This positions the projection 9 substantially Vin the dotted line position shown in Fig. 5. When the legs are swung upwardly 'into transit Vyposition, they swing counter-clockwise, and the projection `9' moves from the dotted line position to the full line position. In this action it engages the member 8D, causes it to swing, and the linger 82 'causes the pawl to swing out of engagement with'the ratchet to thus release the brakes.

At this point the general operation might best Normally, the

, :(not shown)` and this causes' movementof the fmovableelement in the booster 43. This action and this shifts the pin 28 upwardly. The upward shift of the pin rocks the member and shaft `45,'an`d the brakes are applied hydraulically.

VKTo unconplethe tractor and semitrailer, the

vinto engagementwith the arm 3|.

the member 31, and this swings the clutch 3.0 NOW HP0 depression of the'brake'pedal the pin'21\is"-ele vated by the arm 8i, and this rocks the'arm 58.

This results in a rocking" movement of the sleeve 53, by rod 55, and a retraction of the locking member 20 where it is held in retracted position by the detent 2l. Also, this action causes the nger 62 to move into interlocking engagement 'with the arm 46 by reason of the cam 6B (Figs.

8 and ll). The position ofthe parts are vthus maintained due to the locking member of *the draft latch22. The operator inthe cab now resition. Nowy the operator again depresses the brake pedal (not shown) and this time the brakes may be applied hydraulically, as above described, because of the rocking of the shaft 45 through the means of the arm 46. At the same time the shaft is 'rocked due to the interlocking larrangement of 46 andZ, andthebrakes are ap plied mechanically by the rocking of the shaft 5B and the actuation of the rod 5I, the swinging of the ratchet 'l2 and the applying'oi the brakes throughk the brake rods 1.

An important item now makes itself apparent.

. With the brakes thus `applied and heldapplied by the pawl and ratchet the operator releases-the brake pedal to allow the pin 28 to lower, and this takes the load of the brake application oil? of the lhydraulic mechanism. Now the operator drives the tractor forwardly and uncouplesfin which action the service bar pullsthe supporting'legs 8 into supporting position, and the semi-trailer vleases the holding of the member 31 and they `clutch member 3l! shifts back to thefFigflB- pois disconnected from the tractor. As long as the trailer remains parked in this lmanner the brakes are held mechanically and the hydraulic` mechanism is released of brake-applying pressure.

Therefore, any minor leakage :of the fluid 'used in` 1 the hydraulic system may take place without affecting the application orr` the holding of the brakes in applied position. When the brakes are applied lthe spring 52 vis compressed, and the spring normally holds the shaft 5!) positioned' in brake-released position. The spring normally positions the `members 6l`so that the nger 62 may be projected into proper cooperating relationship with the arm 46.

If at any time it is necessary to release thef brakes while the trailer is parked, this may be done by swinging the handle 19 vto release the pawl. The semitrailer may also be equipped with means for re-applying the brakes, which will be presently described. In making a connection between tractor and semitrailer, the tracto!` is backed into the trailer, and when the king pin is in its rearmost position, the draft latch swings, as above described, to locked position, thus releasing the locking member 2li so that it'shifts to locking position as shown in' Fig. l.1.6. VAs the struts or legs 8 reach inoperative position, the projection 9 causes actuation of .the pawlto release the mechanical operation of thebrakes. This causes disengagement between the shafts l5 and 50 by reason of the rocking movement of the sleeve 53 and the retracting of the nger 82"from the Fig. 11 to the Fig; 9 position.

Now the member 2i! is actedupon by means such as a spring'so that it normally assumes locked position shown in Fig. 16. Thisspring may be associated with hand operated `means for releasing the latch from a position on or near the trailer The member 56, as illustrated, is in the form of va`be1l crank having a connectiont' with another bell crank 8i in turn connected to a rod 82 acted upon by a spring 83. This is the spring that normally holds the locking member 20 projected into locking position.

On the end of the rod 82 is a handle 84 which may be manipulated to release the locking member of the latch. If. a full automatic control is not desired, then the handle 84 and associated parts may be used, or it may be desirable to ernploy this mechanism with the automatic mechamsm.

The brakes may be applied by hand by the mechanical means, and for this purpose a rod 85 is attached to the shaft 5B for rocking the shaft. The end of the rod 85 may extend to the forward end of the trailer frame where is has a oneway ball and socket connection 86 with a lever 81 pivoted as at S8. This lever may be arranged so that it may be extended in order to obtain an adequate mechanical advantage, and to this end a handle portion 39 is pivotally mounted to the lever as at 90. This handle portion is arranged to be swung into alignment with the part 87 and be fastened thereto through the means of lug 9|. This, in eect, forms a folding handle which is folded up in use, as shown in Fig. l. When the brakes have been released from the parked trailer they may again be applied by the manual swinging of the lever 81 to rock the shaft 50 and apply the brakes in a manner as above described.

Thus it will be seen that the semitrailer brakes are normally hydraulically actuated during operation and may be applied and held applied by mechanical means operable either from the tractor cab or from the side of the trailer frame when it is desired to uncouple the tractor and semi-trailer. Also the brakes may be released and reapplied during the parking of the semitrailer. Notwithstanding the fact that the trailer brakes are hydraulically actuated in transit, and notwithstanding the fact that they may be applied from the cab of the tractor for release purposes, the hydraulic mechanism is relieved from brake applying pressure While the trailer is parked.

We claim:

1. In a tractor semitrailer combination, brakes for the wheels of the semitrailer, hydraulic means on the trailer for operating the brakes, means on the tractor operable to apply the trailer brakes through the said hydraulic means, mechanical means on the trailer for operating and applying the brakes, means in the mechanical means for holding the brakes applied upon tractor semitrailer separation, means on the trailer for releasing the holding means for release oi' the brakes, and means on the trailer for reapplying the brakes by said mechanical means.

2. In a tractor semitrailer combination, brakes for the wheels of the semitrailer, hydraulic means on the trailer for applying the brakes, mechanical means on the trailer for operating and applying the brakes, means on the tractor for exerting brake-applyingk pressure, means operable at will for selectively delivering the brake-applying pressure to the hydraulic means alone and to the mechanical means, and means in the mechanical means for holding the brakes applied for tractor semi-trailer separation to thereby relieve the hydraulic means on the work of holding the brakes applied.

3. In a tractor semitrailer combination, brakes for the wheels of the semitrailer, hydraulic and mechanical brake-applying means on the semitrailer, means on the tractor operable to deliver brake-applying forces to the hydraulic means, means operable at will to direct the brake-applying forces on the tractor to the mechanical means to apply the brakes by the mechanical means,

and means in the mechanical means for holding 5 the brakes applied upon tractor semitrailer separation to relieve the hydraulic means of brakeapplying forces.

4. In a tractor semitrailer combination, brakes for the wheels of the semitrailer, hydraulic brake- ,10

the king pin for operating the hydraulic and me- '15 chanical brake-applying means, and means on*l the tractor for selectively shifting one of said pins.

5. In a tractor semitrailer combination, brakes for the wheels of the semitrailer, hydraulic meansO on the semitrailer for applying the brakes, a draftU coupling including a king pin, an axially shiftable pin in the king pin, means on the tractor for applying the brakes hydraulically through the shifting movement of said pin, mechanical.;5 brakes on the semitrailer, and means for establishing an operable connection between the mechanical 'brake-applying means and the hydraulic brake-applying means, whereby shift of the pin in the king pin operates both the hydraulic meansl ,30

and the mechanical means.

6. In a tractor semitrailer combination, brakes for the wheels of the semitrailer, hydraulic means on the semitrailer for applying the brakes, a draft -coupling including a king pin, an axially shift-.35

able pin in the king pin, means on the tractor for applying the brakes hydraulically through the shifting movement of said pin, mechanical brakes on the semitrailer, means for establishing an operable connection between the mechanical brake-` fm applying means and the hydraulic brake-apply--" ing means, whereby shift of the pin in the king pin operates both the hydraulic means and the mechanical means, and means in the mechanical brake-applying means for holding the brakes ap- 4r,

plied upon tractor semitrailer separation.

7. In a tractor semitrailer combination, a king pin on the tractor having an axially shiftable pin therein, a draft coupling means on the trailer for receiving the king pin, brakes for the wheels/ of the semitrailer, hydraulic brake-applying means on the semitrailer including anl element associated with said pin, means on the tractor for shifting the pin to apply the brakes through the hydraulic means, mechanical brake-applying 5.', means on the semitrailer disassociated with the"Y hydraulic brake-applying means, means operable to establish an operable connection between the mechanical brake-applying means and said element, whereby movement of said pin actuates both the hydraulic means and mechanical means, 4

and means in the mechanical means for holding the brakes applied.

8. In a tractor semitrailer combination, a king pin on the tractor having an axially shiftable pin therein, a draft coupling means on the trailer for receiving the king pin, brakes for the wheels of the semitrailer, hydraulic brake-applying means on the semitrailer including an element associated with said pin, means on the tractor for shifting` the pin to apply the brakes through the hydraulic; means, mechanical brake-applying means on the semitrailer disassociated with the hydraulic brake-applying means, means on the tractor operable to establish an operable connection betweenl both` the hydraulic means'and mechanical means, andmeansin4 the mechanical means the brakes applied.

9.v In" a tractor semitrailer combination, a king pin on the tractor having'an axially shiftable pin therein, avdraft coupling means on 'the trailer for receiving the king pin, brakes for the wheels of the semitrailer',"hydraulic brake-applying' means on the semitrailer including an element associated Wth"said'pin,"'means on'the tractor for shifting the pin t'oj apply thebrakes through the hydraulic means, means Voperable to condition the coupling means for tractor semitrailer separation, mechanical brake-applying means'on the' 'semitrailer disassociated from the hydraulic brake-'applying means, means voperable to establish a connection between Vthe mechanical brake-applying'means and said element of the hydraulic brake-applying means upon 4vmovement ofthe means operablen to condition the draft coupling for tractor, semitrailer separation, and means in the mechanical brake-applying means for holding the trailer brakes applied upon tractor semitrailer separaion.

'10Q In a tractor semitrailer combination, a king pin on the tractor having an axially shiftable pin therein, a' draft coupling means on the trailer for receiving the `king pin, brakes for the ywheels of thev semitrailer, hydraulic brake-applying means on the semitrailer including an element associated Withl said pin, means on thel tractor for shifting the'pin to apply the brakes through the hydraulic means, means on the tractor operable to condition the coupling means for tractor semitrailer separation, mechanical brake-applying means on the semitrailer disassociated from the hydraulic brake-applying means, means operable to establish a connection between the mechanical brakeapplying means and said element of the hydraulic brake-applying means upon movement of fthe means operable to condition the draft coupling for tractor semitrailer separation, and meansin the mechanical brake-applying means for holding the trailer brakes applied upon tractor semitrailer separation. 4

11. In a tractor semitrailer combination, a king pin on the tractor having an axially shiftable pin therein, a draft'coupling means on'the trailer for receiving the king pin, brakes for the Wheels of the semitrailerfhydraulic brake-applying means on the semitrailer including an element associated with said pin, means on the tractor for` shifting the pin to apply the brakes through the hydraulic means, means on the tractor operable to condition the coupling means for tractor semitrailer separation, mechanical brake-applying means'on the semitrailer disassociated from the hydraulic,

` brake-applying means, means operable to estab-v lish a connection between the mechanical brake-` pin on the tractor having two axially shiftable service pins therein, draft coupling means on the semitrailer for receiving the king pin, brakes for for holding the semitrailer, hydraulic brake-applying means with one of the service pins, means on the tractor operable to 'shift said one'service pin for applying the trailer brakes hydraulically, means on the tractor shiftable to establish a connection between the other service pin 'and' said means on the tractor for shifting said other pin, mechanical brake-applying means on thesemitrailer independent" of the, hydraulic brake-applying means,

means operable upon shift of saidl other pin` yfor establishing a connection between the hydraulic means and mechanical means whereby'shiftof the Allrst mentioned service pin actuatesboth the hydraulic'and mechanical means, andrneans in the mechanical brake-applying means' forholding the brakes applied as the forces for shifting 'the rst service pin are relieved.

13. In a tractor semitrailer combination, a draft coupling including a king pin on the tractor, coupling means on the semitrailer, an axially shiftable service pin in the king pin, brakes forjthe semitrailer, transit brake-operating means comprisingr hydraulic means operable upon shift of the service pin, means on the tractor for shifting the service pinmechanical brake-applying means on the semitrailer disassociated from said service pin, a secondaxially shiftable service pin the king pin, means operable at will to associate said second p in withthe said means on the tractor for ,L

axial shift thereof, means on the semitraileroperable upon shift of the second service pin to condition the coupling for tractor semitrailer separation and for establishing an operable connection between the mechanical brake-applying means and the first mentionedservice pin, whereby shift of the rst mentioned service pin actuates the hydraulic and mechanical brake-applying means, and means in the mechanical brake-applying means for holding the brakes applied upon tractor semitrailer separation. .l

14. In atractor semitrailer combination, a draft coupling including a king pinion the tractor, coupling means' on the semitrailer, 'an axially shiftalolev service pin in the king pin, brakes` for. the semitrailer, transit brake-'operatingv means comprising hydraulic-means operable upon shift ofthe service pin, means on the tractor for shifting the service pin, mechanical brake applying means on the semitrailer disassociated from said service pin,.`a second axially shiftable service pin in thekingpin, means operable at will to' asso,- ciate said second pin with the -said means 01,1 `the tractorI for axial shift thereof, means on the semitraileroperable upon shift of the second service pin to condition the coupling for tractor semitrailery lseparation and for establishing an oper- `able connection between the mechanical brakeapplyingv means andthe rst mentioned servicel pin, means for maintaining the coupling conditioned for tractor semi-trailer separationl and for maintaining the operable relationship between themechanical brake-applying means and the first' mentioned pin when thev forces delivered to the second service pin are relieved, whereby axial shift of the first mentioned servicev pin actuates both the hydraulic and mechanical brake-applying means, means in the mechanical brake-applying means for holding the brakes applied upon tractor semi-trailer separation, saidk means which maintains the coupling conditioned for tractor semi-trailer separation kand which maintains the operable relationship between the first mentioned service pin and the mechanical brakes being automatically rendered ineffective on the semitrailer having an 'element associated uponrecoupling of the king pin with the coupling means on the semitrailer.

15.',In a tractor semitrailer combination, a draft coupling including a king pin on the tractor, coupling means on. the semitrailer, an axially shiftable service pin in the king pin, brakes for` the semitrailer, transit brake-operating means comprising hydraulic means` operable upon shift of the service pin, means on the tractor for shifting the service pin, mechanical brake-applying means on the semitrailer disassociated from said service pin, a second axially shiftable service pin in the king pin, means operable at will to associate said second pin with the said means on the tractor for axial shift thereof, means on the semitrailer operable upon shift of the second service pin to condition the coupling for tractor semitrailer separation and for estabi lishing an operable connection between the meposition upon tractor semitrailer connection,

I for the semitrailer,

hydraulic brake-applying means operable upon movement of the supports to folded position for actuating the brake-holding means to release the brakes.

16. In a tractor semitrailer combination, brakes hydraulic brake-applying means on the semitrailer, a draft coupling including coupling means on the semitrailer and a king pin on the tractor, a service pin axially shiftable in the king pin and associated with the means, mechanical brakes on the semitrailer disassociated from the service pin, means on the tractor including a clutching device for shifting the service pin to apply the trailer brakes hydraulically, a second axially shiftable service pin in the king pin, means for conditioning the clutch so that actuation of the said means on the tractor shifts the second vservice pin, means operable by shift of the second service pin to establish an operable relationship between the mechanical brake-applying means and the first mentioned service pin, whereby shift of the first mentioned service pin actuates the mechanical brake-applying means, and means in the mechanical brake-applying means for holding the semitrailer brakes applied during tractor semitrailer separation.

17. In a tractor semitrailer combination, brakes for the semitrailer, hydraulic brake-applying means on the semitrailer, a draft coupling including coupling means on the semitrailer and a king pin on the tractor, a service pin axially shiftable in the king pin and associated with the hydraulic brake-applying means, mechanical brakes on the semitrailer disassociated from the service n pin, means on the tractor including a clutching device for shifting the service pin to apply the trailer brakes hydraulically, a second axially shiftable service pin in the king pin, means for conditioning the clutch so that actuation of the said means on the tractor shifts the'second service pin, means operable by shift of the second service pin to establish an operable relationship between the mechanical brake-applying means and the first mentioned service pin and for conditioning the draft coupling for tractor semitrailer separation, whereby shift of the first mentioned service pin actuates the mechanical brake-applying means, and means in the mechanical brakeapplying means for holding the semitrailer brakes applied during tractor semitrailer separation.

18. In a tractor semitrailer combination, a king pin on the tractor having first and second axially shiftable service pins therein, coupling means on the trailer for engaging the king pin, brakes for the semitrailer, means on the tractor for shifting the rst service pin, hydraulic brakeapplying means on the trailer operably associated with the rst service pin and including a rocker shaft, mechanical brake-applying means on the semitrailer including a rocker shaft, means on the tractor for shifting the second service pin, means operable upon shift of the second service pin to operatively connect the second mentioned rocker shaft with the first service pin, whereby upon shift of the first service pin the mechanical brake-applying means is actuated to apply the brakes, and means in the mechanical brake-applying means for holding the brakes applied during tractor semitrailer separation.

19. In a tractor semitrailer combination, a king pin on the tractor having first and second axially shiftable service pins therein, coupling means on thetrailer for engaging the king pin, brakes for the semitrailer, means on the tractor for shifting the first service pin, hydraulic brake-applying means on the trailer operably `associated with the rst yservice pin and including a rocker shaft, mechanical brake-applying means on the semi-- trailer including a rocker shaft, means on the tractor for shifting the second service pin, means operable upon shift of the second service pin to operatively connect the second mentioned rocker shaft with the rst service pin and to condition the draft coupling for tractor semitrailer separation, whereby upon shift of the first service pin the mechanical brake-applying means is actuated to apply the brakes, and means in the me- WILLIAM I-I. WILSON. CHARLES I'I. LAND. 

